High-res MR enterography trumps the standard in Crohn’s work-up

High-resolution MR enterography (HR-MRE) has significantly higher diagnostic accuracy in the diagnosis of bowel ulceration, fistulae and abscesses in Crohn’s disease compared to standard MRI, according to a study published in the September issue of Clinical Radiology.

The results suggest that HR-MRE could be offered as a non-invasive alternative in place of MR enteroclysis in the diagnostic work-up of Crohn’s disease patients, wrote Rakesh Sinha, MBBS, MD, of Warwick Hospital, South Warwickshire NHS Foundation Trust, Warwick, U.K., and colleagues.

Differentiation between minor and advanced inflammation or between superficial and deep ulceration is important because it has bearing on which treatments are offered to patients and how therapeutic response is assessed, explained the authors.

To evaluate the accuracy of HR-MRE relative to standard MRE, Sinha and colleagues evaluated 49 consecutive patients who underwent 51 surgical procedures and received both MRE and HR-MRE prior to surgery. Findings were validated against surgical and histological results to determine accuracy.

Results showed the sensitivities and specificities of MRE and HR-MRE in detecting abnormal segments were 0.82 and 0.95 compared with 0.86 and 0.95, respectively. HR-MRE was statistically significantly more sensitive than MRE in identifying deep ulcers, fistulae and abscesses. HR-MRE was also significantly more sensitive to superficial ulcers, but both HR-MRE and MRE only had moderate sensitivity in this area.

“The lower sensitivity in the detection of superficial ulceration is because MR studies depend on luminal distension using a single contrast agent, and this precludes detection of small mucosal lesions,” wrote Sinha and colleagues, who added that deep, transmural ulcers are easily seen within the thickened isointense bowel wall.

In discussing why HR-MRE yielded a higher accuracy, the authors wrote that higher in-plane resolution and high-quality multiplanar images used for review should aid in the detection of fistulae and ulceration and lead to increased accuracy. Radiologist experience, high quality bowel preparation and volume of oral contrast medium ingestion would also affect diagnostic results, according to Sinha and colleagues.

Bowel ulcers and a mural enhancement ratio of greater than 1.85 were strong predictors of advanced inflammation. “As HR-MRE has significantly greater accuracy in the detection of bowel ulcers, this technique may be better suited to accurately assess the degree of bowel inflammation,” wrote the authors, who suggested reserving MR enteroclysis for cases with obstructive features or suspected strictures.